A catastrophic event caused by a fat person. Often happens at fast-food places, hospitals or at you mothers house.

Liam: "Damn there was a fire at Mc. Donalds yesterday and no one could get out of there."
Nik: "Why?"
Liam: "No one was slim enough to get out of the doorway."
Nik: "Wow, that was a real fatasstrophe."